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Page last updated at 18:16 GMT, Thursday, 13 May 2010 19:16 UK

Plan to cap Gulf of Mexico oil leak with dome delayed

The 'top hat' containment chamber is lowered into the Gulf of Mexico, 11 May
BP says the new dome should be working later on Thursday or Friday

A new attempt by BP to control the main leak at the Gulf of Mexico oil well disaster site with a steel dome has been put back by a "few days".

Earlier, the British oil giant said it hoped the "top hat", which is now on the seabed, would be deployed by Thursday at the broken pipeline.

An attempt to use a larger containment dome failed on Sunday when it became clogged with ice and gas.

The well is spewing out some 5,000 barrels (210,000 gallons) of oil a day.

The "top hat" is meant to siphon oil into container ships but there is no guarantee that the plan will work, the BBC's Andy Gallacher reports.

The first of two relief wells being drilled is not expected to be ready for some three months.

Human hair

Emergency teams are using several methods in their attempts to deal with the oil at the surface.

Thousands of clean-up crews, soldiers and volunteers have all been deployed to keep the expanding oil slick from damaging the coastlines of four states.

Around 1.5m ft of floating booms are being used as part of the efforts to stop oil reaching the coast, Reuters reports.

A US charity is even making booms out of nylon tights, animal fur and human hair.

Hair donations have been sent from around the world to help make the special booms, which will be laid on beaches to soak up any oil that washes ashore.

Eleven people died when an explosion - thought to have occurred after a surge of methane gas from deep within the well - destroyed the Deepwater Horizon rig on 20 April.

Huge bill

The huge oil spill has so far cost BP - which is in charge of the clean-up operation - $450m (£300m).

The total bill could be as high as $20bn (£13.6bn), analysts say.

"Estimates run from between $3bn to $20bn. Certainly, there's the clean-up costs.

"And the associated lawsuits, which at this stage looks like it could be one of the largest class actions in US history", oil analyst Greg Smith of stock market research house Fat Prophets told the BBC.

"From our point of view, we would think somewhere mid-range - around the $10bn mark," he adds.

Underwater efforts to cap oil leak

Initially, BP tried to lower a 125-tonne, 18-metre (59 feet) high container dome over the main leak on the sea floor. However, this failed when gas leaking from the pipe mixed with water to form hydrates, ice-like crystals, that blocked up the steel canopy.
Instead, engineers have lowered a smaller device onto the site. Dubbed the Top hat, it will sit over the tear in the pipe and partially stop the leak. To prevent the build up of hydrates, methanol is pumped into the top hat to disperse the water and gas.
The top hat is 1.5m (5 feet) high and 1.2m in diameter. Two special side lines are used to pump methanol into the top hat to displace water and gas leaking from the broken oil pipe. This should prevent the build-up of hydrates. Once in place, oil can be pumped up to the surface.
BP plan to lower the original subsea containment dome over the top hat to provide a better seal over the leaking site and pump oil up to the surface. This time, it will be attached to a pipe that can pump warm water into the dome to prevent the build-up of hydrates.
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